This seems to be the report (October 2024)
https://www.nao.org.uk/wp-content/uploads/2024/10/support-for-children-and-young-people-with-special-educational-needs.pdf
https://www.nao.org.uk/reports/support-for-children-and-young-people-with-special-educational-needs/?nab=2
Key conclusions:
"Since 2019, there has been no consistent improvement in outcomes for
children and young people with SEN."
"Families and children lack confidence in a SEN system that often falls short of
statutory and quality expectations. Stakeholders told us that insufficient capacity,
and long waiting times, contributed to low parental confidence."
"DfE does not know with confidence how much capacity should be planned,
and where, to meet future needs."
"State special schools are over capacity which may lead to poor value for
money."
"If unreformed, the SEN system is financially unsustainable."
"DfE has committed to improving the system, undertaking various initiatives,
although there is no evidence these will fully address the challenges"
"DfE has set up programme management processes but has not brought
together its initiatives into a clear actionable plan, making it harder to understand
progress and make decisions."
"DfE has taken steps to tackle local authorities’ immediate financial pressures,
but these will not provide a sustainable system."
"Since 2014, DfE has been aiming for mainstream schools to be more inclusive,
but there is limited evidence of progress."
"The factors influencing rapid increases in SEN can be hard to quantify which
inhibits DfE’s ability to focus on addressing root causes, many of which extend
beyond its remit"
"Although organisations have clear responsibilities, misaligned priorities and
incentives create challenges to a whole-system approach."
"DfE estimates that some 43% of local authorities will have deficits exceeding or close to their reserves in March 2026. This contributes to a cumulative deficit of between £4.3 billion and £4.9 billion when accounting arrangements that stop these deficits impacting local authority reserves are due to end. As such, the current system is not achieving value for money and is unsustainable"
"there remain significant doubts that current actions will resolve the challenges facing the system. None of the stakeholders we spoke to believed current plans would be effective"
So, naturally the thing to do is force more children with SEN into a broken system, and try to have the evidence ruled inadmissible in court.